Cranial nerve examination and how to present it

• The cranial nerve (CN) examination tests nerves I to XII in order, from smell and vision through eye movements, facial sensation and strength, hearing, the palate, tongue and neck muscles.
• It is done with the person seated in good light, using simple tools: a Snellen chart, a cotton wisp and pin, a 256 hertz tuning fork, a pen torch and an ophthalmoscope.
• Each finding can be described as normal or abnormal and traced to one nerve or to the brain-stem pathway behind it.
• The classic localising patterns are third nerve palsy, facial palsy (upper versus lower motor neurone), and bulbar and pseudobulbar palsy.
• Present the findings in nerve order, lead with the most important abnormality, state the negatives that matter, and end with a short summary and differential.

By the end of this page you should be able to:

1. Set up and perform a complete cranial nerve examination in a logical order at the bedside.
2. Choose the right test for each of nerves I to XII and know what normal looks like.
3. Tell an upper motor neurone facial palsy from a lower motor neurone one, and describe a third nerve palsy.
4. Tell bulbar from pseudobulbar palsy from the examination.
5. Interpret a whisper test and bedside tuning fork tests for hearing.
6. Turn a list of cranial nerve findings into a clear spoken or written presentation.

A cranial nerve examination asks whether the twelve nerves and the brain-stem nuclei behind them are working, and whether the problem lies inside the brain stem or outside it. The MSD Manual notes that a process inside the brain stem usually comes with long-tract signs such as spasticity or sensory loss below the head and neck, whereas isolated cranial neuropathies point to a problem outside it.^[1] Finding these clues early is what makes the examination valuable in a first neurological assessment.^[5]

The examination is usually performed after the history, with the person seated and comfortable, at eye level with you. Your eyes and ears do most of the work; the tools (a Snellen chart or handheld near-vision card, a cotton wisp, a pin or orange stick, a 256 hertz tuning fork, a pen torch, an ophthalmoscope) are only aids. Explain what you are about to do before each step, and let the person know they may look away from the light.

• Introduction and consent. Explain that you will test the nerves of the head and neck, why, and that it takes a few minutes. Confirm consent before starting, and respect a request to pause or stop.
• Chaperone. Offer a trained chaperone for any intimate or sensitive examination, and record the offer and response. Most cranial nerve testing is not intimate, but common decency (curtain, gown, a witness when needed) applies.
• Hand hygiene and safety. Clean your hands before and after, and between patients. Do not reuse disposable tongue depressors, cotton buds or gloves.
• Exposure and position. Sit the person upright with the face and neck fully visible in good light, glasses on for vision testing, and any jewellery or head covering moved aside. Have the person describe what they see or hear in their own words rather than prompting them.
• Environment. A quiet room away from distracting noise matters, especially for the whisper and tuning fork tests.
• A neurological screen first. Where time is short, orient the rest of the examination (mental status, motor, sensory, reflexes) before settling into the cranial nerves, so that a focal sign is not missed.

Work head to toe and nerve by nerve: I, then II, then III, IV and VI together, V, VII, VIII, IX and X, XI, XII. This is the order used in standard bedside teaching and keeps the eye tests together and the lower cranial nerves together.

1. Cranial nerve I (olfactory). Smell is tested only when there is a reason (head trauma, suspected anterior fossa disease, or a report of altered smell or taste). Ask the person to close their eyes and occlude one nostril, then hold a familiar, non-irritant odour (soap, coffee, cloves) under the open nostril; repeat on the other side. Alcohol and ammonia test the nociceptive receptors of the trigeminal nerve rather than smell, and are reserved for when malingering is suspected.^[1] A unilateral loss suggests a lesion of the olfactory tract or bulb on that side.

2. Cranial nerve II (optic). Test visual acuity with a Snellen chart for distance vision or a handheld chart for near vision, each eye in turn with the other eye covered.^[1] Test colour perception with standard pseudoisochromatic plates (Ishihara or Hardy-Rand-Ritter). Test visual fields by confrontation in all four visual quadrants, moving your fingers or a wiggling target from the periphery inward. Test the direct and consensual pupillary responses. Perform fundoscopy to inspect the optic discs and retinal vessels.

3. Cranial nerves III, IV and VI (oculomotor, trochlear, abducens). Observe symmetry of the eyes and lids: globe position, asymmetry or droop of the lids (ptosis), and any twitches or flutters. Ask the person to follow a moving target to all four quadrants; note diplopia and the direction in which it occurs. Record anisocoria in a dimly lit room, and test the pupillary light response for symmetry and briskness.^[1] (Physiological anisocoria is common; anisocoria that is larger in the dark suggests sympathetic failure, and anisocoria that is larger in the light suggests parasympathetic failure.)

4. Cranial nerve V (trigeminal). Evaluate the three sensory divisions (ophthalmic, maxillary, mandibular) with a sharp object for pain and by brushing a cotton wisp for light touch; test the corneal reflex by gently touching the lower or lateral cornea. If sensation is lost, examine the angle of the jaw: sparing of this area, which is supplied by the C2 spinal root, suggests a trigeminal lesion rather than a spinal one. Test motor function by palpating the masseter muscles while the person clenches their teeth, and by asking them to open their mouth against resistance. If a pterygoid muscle is weak, the jaw deviates toward the side of the lesion when the mouth opens.^[1]

5. Cranial nerve VII (facial). Inspect for hemifacial weakness: asymmetry is often clearer during spontaneous conversation, especially when smiling. Note a flattened nasolabial fold and a widened palpebral fissure on the weakened side. For each side, ask the person to raise the eyebrows, close the eyes tightly against your fingers, bare the teeth, smile, and puff out the cheeks. Cradle the person's face and try to force the eyes open: you should not be able to. Taste in the anterior two-thirds of the tongue can be tested with sweet, sour, salty and bitter solutions on cotton swabs, testing one side at a time, keeping the tongue protruded so the taste is not detected by the other side. Hyperacusis suggests weakness of the stapedius muscle and is picked up by asking whether sounds are exaggerated on one side, or with a vibrating tuning fork held next to the ear.^[1]

6. Cranial nerve VIII (vestibulocochlear). Hearing is tested first in each ear by whispering something while occluding the opposite ear.^[1] A whisper is heard at close range at about 34 decibels and conversational voice at about 56 decibels; if there is no response, move to 15 centimetres closer and repeat.^[4] Suspected loss should lead to formal audiometry. At the bedside, try the Weber and Rinne tests with a 512 hertz tuning fork to separate conductive from sensorineural loss; they are difficult to do well except in experienced hands, so they are best used as pointers rather than proof.^[1][4] Vestibular function is examined through nystagmus: record its direction, duration and triggers, whether horizontal, vertical or rotary, and whether it appears spontaneously, on gaze or with head movement. Use the head-thrust manoeuvre to separate central from peripheral vertigo, and the Dix-Hallpike manoeuvre for positional vertigo.^[1]

   • Rinne: place the vibrating fork on the mastoid process (bone conduction), then in front of the ear (air conduction); ask which position is louder. Air louder than bone is normal and is also seen in a sensorineural loss; bone louder than air suggests a conductive component of more than 15 decibels.^[4]
   • Weber: place the fork at the centre of the forehead or vertex and ask which side is louder. Central (equal both sides) is normal; lateralisation points toward the better hearing cochlea.^[4]
   • Vestibular clues: if nystagmus becomes absent when the patient wears Frenzel (or +30 dioptre) lenses, it is probably peripheral; direction-changing nystagmus suggests a central cause. Eyes beat away from the side that is not working. A latency of 5 to 10 seconds and fatigue on repeating the Dix-Hallpike manoeuvre suggest benign paroxysmal positional vertigo; positional nystagmus that does not fatigue or have latency is central.^[1][4]

7. Cranial nerves IX and X (glossopharyngeal and vagus). Observe whether the palate rises symmetrically when the person says "ah": if one side is weak, the uvula is pulled away from the weak side. Touch each side of the posterior pharynx with a tongue blade and compare the gag reflex; bilateral absence is normal in some people and is not by itself disease. Listen for hoarseness. If the person is unconscious or intubated, suctioning the endotracheal tube normally triggers coughing.^[1]

8. Cranial nerve XI (accessory). Test the sternocleidomastoid by asking the person to turn the head to one side and then hold it there against your hand while you palpate the muscle on the opposite side. Test the upper trapezius by asking the person to shrug the shoulders against your resistance.^[1]

9. Cranial nerve XII (hypoglossal). Ask the person to stick the tongue out and hold it there. Inspect for wasting, fasciculations and weakness: the tongue deviates toward the side of a lesion.^[1]

Third cranial nerve disorders can impair ocular motility, pupillary function, or both. Symptoms and signs include diplopia, ptosis, and impaired adduction and upward and downward gaze.^[2] The affected eye may deviate slightly out and down in straight-ahead gaze; adduction is slow and may not reach the midline, and upward gaze is impaired. When downward gaze is attempted, the superior oblique muscle causes the eye to adduct and intort (that is, to turn inward and slightly downward). The pupil may be normal or dilated, its response to direct and to consensual light sluggish or absent when the parasympathetic fibres are involved, and mydriasis may be an early sign.^[2]

The pupil is the key to urgency. A dilated, unreactive pupil points toward causes in which the fibres on the surface of the nerve are stretched or compressed: aneurysms of the posterior communicating artery, transtentorial herniation, or meningitis affecting the brain stem. Pupils that are spared are typical of ischaemia of the nerve (often from diabetes or hypertension) or of the midbrain, and partial palsies more often spare the pupil. An intracranial aneurysm can very occasionally spare the pupil, so a painful third nerve palsy still needs urgent imaging whatever the pupil does, particularly if the headache is severe or the person's conscious level is falling.^[2]

A fourth nerve palsy shows as vertical diplopia that is worse on looking down and in (the position used when reading or descending stairs), often with a compensatory head tilt to the opposite side. A sixth nerve palsy prevents abduction of the eye, so the eye sits turned in and the person sees double on lateral gaze. Neither palsy causes ptosis or pupillary change, which is how either is distinguished from a third nerve lesion. Raised intracranial pressure and cavernous sinus disease classically present with isolated abducens palsy, because the sixth nerve has a long intracranial course.

Facial muscles are innervated peripherally by the ipsilateral facial nerve and centrally from the contralateral cerebral cortex. Central innervation is usually bilateral for the upper face (forehead muscles) and unilateral for the lower face. That is why a central (upper motor neurone) facial palsy weakens the lower face while sparing the forehead, allowing the person to wrinkle the forehead, furrow the brow and close the eyes tightly, whereas a peripheral (lower motor neurone) palsy affects the whole half of the face, including the forehead and eye closure.^[3] In idiopathic facial nerve palsy pain behind the ear often comes first, with paresis that reaches its maximum within 48 to 72 hours; the affected side becomes flat and expressionless, with a widened palpebral fissure and an eye that will not close. Sensory examination is otherwise normal, though the external auditory canal and the mastoid area may be tender. If the lesion is proximal to the geniculate ganglion, salivation, taste and lacrimation may be impaired and hyperacusis may be present. Sensory loss beyond the small patch behind the ear, or the development of other neurological signs, or a gradual course, points away from an idiopathic palsy toward a structural or infiltrative cause and should prompt brain imaging.^[3]

A bulbar palsy is a lower motor neurone syndrome of the lower cranial nerves (V, VII, IX, X, XII) and the muscles they supply. It produces dysarthria that is nasal and weak, dysphagia, a weak or absent cough, pooling of saliva, a weak gag and a tongue that may be wasted and fasciculating. It points to disease of the cranial nerve nuclei, their peripheral nerves, or the neuromuscular junction and muscle. Pseudobulbar palsy is the mirror image: an upper motor neurone syndrome of the corticobulbar pathways, producing spastic, strained dysarthria, a brisk gag, jaw spasticity with an exaggerated jaw jerk, emotional lability (pathological laughing or crying), and often a brisk snout or sucking response. The facial movements are weak but the forehead is largely spared in a way that can mimic a central palsy; the tongue is small and stiff rather than wasted and fasciculating. Telling the two apart decides whether to look for a structural lesion of the lower brain stem, neuromuscular disease, or a bilateral pyramidal lesion.

A sound localising rule is that cranial nerves are peripheral outside the brain stem until proven otherwise. The presence of long-tract signs such as spasticity or sensory loss below the head and neck places the lesion inside the brain stem and points to an intra-axial process. Specific combinations are memorable:

• Isolated loss of smell suggests a frontal lesion or trauma to the olfactory pathway rather than a diffuse process.
• A relative afferent pupillary defect localises to the optic nerve or severe retinal disease on that side, before the chiasm.
• Bitemporal hemianopia (not tested on confrontation as precisely as with formal perimetry, but worth noting) points to chiasmal disease.
• Multiple cranial neuropathies on one side suggest a cavernous sinus, petrous apex, skull-base or jugular foramen lesion, depending on which nerves are grouped.
• Hoarseness with a normal palate and no other lower cranial findings should raise a compressive lesion of the recurrent laryngeal nerve in the neck or mediastinum rather than a brain-stem process.

The presentation is a medical summary, not a list of every test you performed. Say it in this order:

1. Open with the most important finding (or the absence of any important finding). Name the pattern if you see one: "There is a right third nerve palsy" or "The cranial nerves are intact to testing."
2. Then report nerve by nerve, I to XII, in one or two short sentences per nerve, but group the normal nerves ("Cranial nerves I, V, VII to XII are intact"). Do not repeat every subtest you did; state the exception, not the whole normal.
3. State the relevant negatives. If the facial palsy is lower motor neurone, say "forehead movement is also weak, so this is a lower motor neurone palsy" rather than leaving the distinction assumed. If vision and fields are normal, say so, because that rules out an optic nerve lesion.
4. Give the summary sentence. In one sentence say what you think the likely level is: nerve, brain stem, or higher.
5. Give the differential in one sentence. Two or three plausible diagnoses, ranked by likelihood and danger, not a textbook list.
6. Close with the plan in one sentence if you are presenting to a senior: what you would do next.

The matching written entry uses the same order but shorter: "CN III (R) palsy: ptosis, mydriasis, eye down and out, limited adduction/up-gaze; conjugate gaze otherwise intact; fundi normal; other CNs intact. ?? posterior communicating artery aneurysm versus ischaemic (pupil-sparing) palsy; Needs urgent imaging." Only abbreviations you have explained (CN, R, UMN) are allowed. Write the normal as "CN I-XII intact (vision, fields, fundoscopic)" rather than a sentence.

Illustrative normal (invented patient). "Mrs Davis, 42, here for fatigue: visual acuity normal on near and distance charts in both eyes; fields full to confrontation; fundi normal; eye movements full with no nystagmus; pupils equal and reactive; facial sensation and facial movements symmetric; hearing normal to whisper and tuning forks; palate and tongue midline and strong, gag present; neck and shoulder power normal. Cranial nerves I to XII are intact."

Illustrative abnormal one (invented patient). Spoken: "This is a 68-year-old man with a sudden, painful, right-sided ptosis. There is a right third nerve palsy: the right eye is down and out, the lid droops, the pupil is dilated and does not react to light, and upward and medial gaze are limited; downward gaze is preserved via the trochlear. Facial sensation, corneal reflexes, facial movements and the remaining cranial nerves are intact. I think this is a compressive right oculomotor palsy, and the dangerous possibility is a posterior communicating artery aneurysm; the helpful alternative is a pupil-sparing microvascular palsy if the pupil proves to be spared. He needs urgent vascular imaging."

Illustrative abnormal two (invented patient). Spoken: "This is a 24-year-old woman with sudden left facial weakness starting overnight after an earache. She cannot raise her left eyebrow, close her left eye against resistance or smile on that side; the nasolabial fold is flat and the eye does not shut, but taste is preserved. The right side is normal. This is a lower motor neurone facial palsy on the left, with the upper face affected as well as the lower. The likely diagnosis is idiopathic facial nerve palsy, but Ramsey Hunt is a close alternative given the ear pain, so I would look in the ear canal and consider treatment urgently."

Illustrative abnormal three (invented patient). Spoken: "This is a 71-year-old man with six months of progressive difficulty swallowing and a heavy, nasal voice. The tongue is wasted and fasciculating, the jaw jerk is absent, the gag is weak on both sides and the palate does not move well; the facial movements and eye movements are normal and the limb examination is normal. This pattern is a bulbar (lower motor neurone) palsy, and the serious alternatives are motor neurone disease and a structural lesion at the foramen magnum; he needs a swallowing assessment and brain-stem imaging."

These findings should change your pace and usually warrant same-day senior review or urgent imaging:

• A painful third nerve palsy, especially with a dilated pupil, a rapidly worsening headache, or any drop in conscious level.
• Sudden monocular visual loss, or a new relative afferent pupillary defect.
• Papilloedema, which suggests raised intracranial pressure until proven otherwise.
• Bulbar weakness with respiratory compromise, or rapid progression over hours to days.
• An expanding mass, new seizure, or meningism accompanying any cranial nerve deficit.
• Bilateral sixth nerve palsies or any sign pointing to raised intracranial pressure.
• Facial palsy accompanied by vesicles in the ear, severe otalgia, or hearing loss, which suggest Ramsay Hunt syndrome and fluridine-responsive herpes zoster.
• Dysphagia with aspiration risk before a diagnosis is reached.

• The examination costs nothing beyond light, a Snellen chart or a near-vision card, a pin and cotton, and a tuning fork. Form vision and fields by confrontation are the most useful bedside tests.
• Formal audiometry and cross-sectional imaging may not be available; a clearly progressive, asymmetric, or painful cranial neuropathy should prompt referral before a firm diagnosis is made.
• Keep a spare 256 hertz tuning fork and a set of Ishihara plates if any funding is available; colour vision is often the first thing lost in optic nerve disease and is the cheapest test of the second nerve.
• Train one person in each clinic to screen vision and eye movements reliably and to record negative findings, so that disease is caught before it advances.

• Testing vision without occluding the other eye, or forgetting to test near and distance.
• Assuming cranial nerve I is part of the routine examination; it is only tested when indicated, and irritants such as ammonia test the trigeminal nerve.
• Forgetting to look at the pupils in a dim room: anisocoria is easy to miss in bright light.
• Treating all facial weakness as a stroke: a central palsy spares the forehead, a peripheral one does not.
• Calling every palsy "third nerve palsy" without noting whether the pupil is involved; pupil involvement changes the urgency.
• Skipping the lower nerves (IX to XII): a bulbar palsy can be silent until late.
• Presenting a long checklist instead of a summary; examiners remember the first sentence and the last.
• Failing to state the normal cranial nerves: the negatives carry as much weight as the abnormality.

• Test the nerves in order (I to XII), grouping the eye nerves and the lower nerves.
• Cranial nerve I is only tested when there is a reason, using non-irritant smells.
• Cranial nerve II means acuity, colour, fields, pupils and fundi.
• Cranial nerves III, IV and VI are tested together, with ptosis, eye movements and pupillary responses in dim light.
• Trigeminal testing covers three sensory divisions, the corneal reflex, and masseter and pterygoid strength.
• A central facial palsy spares the forehead; a peripheral one takes the whole half of the face.
• Hearing screening is by whisper test, supported by 512 hertz tuning forks and formal audiometry when needed.
• The palate, gag, tongue and neck muscles are the lower cranial nerves V (through XII).
• Bulbar palsy is lower motor neurone (wasted, fasciculating tongue, weak gag); pseudobulbar is upper motor neurone (spastic dysarthria, brisk gag, emotional lability).
• Present abnormal findings first, then the nerve-by-nerve report, then a summary and differential.
• Record the normal nerves concisely instead of listing every subtest.
• Retest any abnormal part and re-examine the patient.

Much of the routine examination still applies. Smell and vision cannot be tested formally. Pupils, eye movements and the corneal reflex can be assessed: in coma the eyes may show roving movements, periodic alternating gaze, or an ocular bobbing that localises to the brain stem. Oculocephalic (doll's eye) movements are tested when the cervical spine is cleared: turning the head should make the eyes move the opposite way; absence suggests a lesion of the pontine or midbrain pathways. Cold water caloric testing is a more powerful stimulus and should be performed only by staff trained to interpret it. The gag and cough reflexes are tested by suctioning. The tongue cannot be protruded to command, but you can look for atrophy and fasciculation and for deviation when a painful stimulus is applied. Facial movement is assessed by observing grimacing to supraorbital pressure or tracheal suction. A single dense hemiparesis with facial sparing or involvement helps to distinguish cortical from brain-stem lesions.

Adapt rather than abandon. For vision, use a picture chart or the "E" or "C" test; for fields, use confrontation with a moving target that the person can follow passively observed by you. For speech and comprehension, point to objects instead of asking for verbal answers. For facial movement, imitate the movement for the person and ask for a mechanical copy. For swallowing, observe the patient with a teaspoon of thickened liquid under the guidance of the speech and language therapist rather than rushing to a formal bedside test.

Play changes the examination. Vision is tested with pictures or matching cards appropriate to age, colour naming replaces plate reading, and facial mimicry games test the facial nerve. The whisper test becomes a game of whispering the name of a familiar object. Lower cranial nerves are examined while the child laughs, cries and sticks the tongue out for a sweet. In infants, rooting, sucking and the gag reflex are the cranial nerve examination.

A good presentation lasts under a minute and has five sentences. Practise the shape until it is automatic:

1. "This is a (age)-year-old (person) presenting with (the one problem that brought them)."
2. "On cranial nerve examination I found (the key abnormality and its pattern, or 'the cranial nerves are intact to testing')."
3. "The relevant negatives were (fields, fundi, facial and limb examination, and so on)."
4. "My localisation is (nerve, brain stem or higher pathway), and the likely causes are (two or three, ordered by likelihood and danger)."
5. "I would like to (one or two practical next steps)."

Useful shorthand, once you have expanded every abbreviation once in your written note: CN, R or L, UMN, LMN, VA, fields, fundi. Avoid strings of abbreviations in speech; say "cranial nerve three" out loud and "third nerve palsy" in the notes. If two examiners disagree about a finding, re-examine in front of them rather than arguing about it.

Phrases that work include "the cranial nerves are intact to the testing I performed", "there is no new deficit since the last documented examination", and "vision and fields were not reliably testable because (reason), so (alternative) has been arranged". Saying what you could not test is more useful than implying an examination you did not do.

A normal cranial nerve examination is often under-recorded, which makes later comparison impossible. Write the minimum that proves you did each part: "Visual acuity normal to near and distance charts; fields full to confrontation; fundi: discs normal, no papilloedema; eye movements full, no nystagmus; pupils equal and reactive, no anisocoria in dim light; V sensation symmetric, corneal reflex present; VII symmetric, forehead movement present; VIII hears whisper both ears; IX/X palate rises centrally, gag present; XI and XII normal." Even if you do not carry a measuring ruler, noting "pupils equal and reactive, no anisocoria in dim light" is far better than "CN intact".

Not every problem has a single nerve at fault. Fatigue, anxiety, pain and functional disorders can produce inconsistent findings that do not fit an anatomical pattern. The clues are variability from one examination to the next, findings that improve when the person is distracted, and the presence of non-anatomical boundaries. In such cases, repeat the examination on a different day, test the effort given (for example by asking for repeated maximal contractions), and look for the well-defined "positive" functional signs rather than treating the examination as failed. Cranial nerves are often genuinely normal in people with widespread functional symptoms, and saying that plainly is a useful result.

Examiners vary in how strictly they score the examination. The points most commonly argued about are whether a subtle ptosis is present, whether nystagmus is truly direction-changing, and whether a facial movement is slightly weak on one side. Reduce these arguments by using the same target, the same lighting and the same position each time, by testing repeatedly rather than taking one snapshot, and by writing down a one-word descriptor ("subtle", "marked", "equivocal") when you are unsure. If a finding is equivocal on the day, re-examine tomorrow before committing to it in a scan request.

Plain-text related topics include: neurological examination, examination of the motor system, examination of the sensory system, stroke and transient ischaemic attack, idiopathic facial nerve palsy, posterior communicating artery aneurysm, optic neuritis, vertigo and vestibular disorders, hearing loss, motor neurone disease, dysphagia, and raised intracranial pressure. These MedGrasp topic links are listed as plain text until the corresponding pages are verified.